In the metabolic syndrome (MS), a condition that associates three or more pathologies such as hypertension, central obesity, type II diabetes, insulin resistance and dyslipidemias, the kidneys are severely affected. The pathological alterations in the kidneys, associated with MS, may be modified by sex hormone levels. In general, estrogens are a protection against the development of cardiovascular and renal diseases in humans and experimental models, but androgens may have an opposite effect. Among the metabolic systems that can be modulated by sex hormones in the kidney, the more important are: renin-angiotensin-aldosterone system, arachidonic acid metabolism, nitric oxide system and renal extra-cellular matrix proteins. These are metabolic pathways normally associated, in order to maintain the most efficient functioning of renal hemodynamics. There is a close interrelationship between sex hormones and some pathways involved in the metabolic syndrome; also pathways can modulate each other. The circulating concentrations of hormones may determine the degree of overall pathological alterations in the syndrome.